It is known as disclosed for example in the Drossbach U.S. Pat. No. 3,391,424 granted July 9, 1968 to provide apparatus for manufacturing perforated corrugated tube in which cutter means adjacent the exit end of traveling molds is operative to cut longitudinal grooves through the wall thickness of the valleys of the corrugations. In a perforated corrugated tube made with the apparatus of said U.S. Pat. No. 3,391,424 the radial heighth of the corrugations is decreased at the locations of the perforations, and hence, the crush strength of the corrugated tube may be substantially decreased in view of such strength being related to the cube of the heighth of the corrugations. Moreover, with the apparatus of U.S. Pat. No. 3,391,424 all of the corrugations of the tube are perforated along lines extending parallel to the axis of the tube, and therefore, the crushing strength weaknesses extend throughout the length of the tube along such lines of perforations.